I have the privelege to present information and images about Jack's Tuna Gun to you now.

Many years ago in Mexico, Marty Passos, Hector Escalante and Jack Prodanovich  dove in the clear, deep, submarine canyon at Friales, Baja California del Sur. Those were the seminal years of development which led to the creation of the Tuna Gun.  Then, large amberjack (Seriola colburni) swam in the deep water of the submarine canyon.  This canyon starts at the shore and rapidly decends to a thousand feet deep, within a mile of the warm sand beach.  These pioneering bluewater freedivers would swim out from the beach and, within a few minutes, would be in deepblue "oceanic water".  Giant fish would circle them and sombody would shoot. Downward the fish would charge. The speargun reel would almost get stripped of line. The diver would hang on and get towed into the depths, only to release the reel's drag at the last second and desperately crawl back to the surface for precious air. It was a dangerous, exhilerating sport. The 100 lb. amberjack could easily hold it's position, fighting to survive, at 400 feet deep.  It was nearly impossible for these "iron-divers" to slowly crank the amberjack up from the depths. The Friales submarine canyon was a proving ground for the next step.

Jack's inventive mind understood the mechanical advantage a pully would lend to the equation.  He realized that if a pully was attached to the "shooting line" (to the arrow in the amberjack), and a line through the pully went to a float,the diver could lift almost twice as much weight as he could without the pully. (The most lead weight I have ever been able to lift off the bottom of the ocean is 33 lb., and that was only momentarily).

Initially, Jack used a "Tether Ball" as his float.  The line went through a pully to his reel on his speargun.  If he shot a fish, it would run and tow the line down into the depths.  If he locked up the brakes on the reel,the line would pass through the pully and the tether ball would decend toward the fish underwater, towing the pully.

Imagine this scenario happening at several hundred feet straight down.  If the tether ball had enough bouyancy, it would pull the fish up from the depths and the diver would only experience 50% of the effort he had usually exerted. All the diver had to do was to reel the line in and the fish would come up with reasonable effort.  Remember, a man only has a minor fraction of the strength of a fish of this size.  This was a technological breakthrough for Marty, Hector and Jack.  Now they could shoot really big fish and surely land them.  The deep waters of Friales submarine canyon and large amberjack foretold the bluewater future of spearfishing. Marty Passos, Hector Escalante and Jack Prodanovich had pioneered the steps from reef spearfishing to bluewater hunting. No longer would grouper or black seabass be the only fish a spearfisherman would persue.  The bluewater thresholdhad been crossed.

Jack's Tuna Gun has a 6" Wally Potts Reel which holds 1000 feet of high-strength parachute cord. While swimming Jack towed the floats 30 feet behind the speargun.  The floats are attached to the reel line and the shooting line at the pully. The spring clip on the left side of the handle keeps the float from pulling line from the reel while swimming forward, yet allows a quick release if a fish is shot.  The prong at the top of the handle is a line latch.  This device drops down to allow the shooting line to deploy.  This is a feature typical of all Jack Prodanovich handles.

The operation of the float rig is quite ingenious.  From earlier experiments, Jack learned that a large fish would take the float under water.  The line passed through the pully until the float lodged against the pully and stopped.  Jack rigged-up a canister inside of the floats which would hold a parachute (sea anchor) to help slow the speared fish.  A plastic tube rests over the line, so that when the float jams against the pully, the tube opens up the stainless steel spring clip releasing the parachute for added pressure on the fish.

In order for the system to work properly, the float must not have excessive bouyancy.  The system is designed so that the diver can stay swimming on the surface while the fish pulls the float under water.  To lift the fish the diver reels in line.  There is a 2:1 mechanical advantage because of the pully.

This speargun is relatively compact and streamlined when fully rigged.  It is equivalent to a 48" gunbody because the lapped slings are seperated by 8".  From the next picture you can see the muzzle of the gun with openings for rubberbands (In storage when gun is not in use.) The large "stem-point" tip can be seen not protruding past the front of the gun.

Jack shot numerous large wahoo with this gun at the Revilla Gigedo Islands.  Several divers have had the privelege of trying it out.  Bill Hammel says that yellowtail just freeze when the big shaft hits them.  Jack shot his last 60 lb. wahoo at age 83 years old at Soccoro Island.

Ironically Jack was never able to sink a spearshaft from this gun into a yellowfin tuna at Soccoro Island.  He made numerous trips with his associate PatDaley on vessle Megaladon, but never saw a giant yellowfin through his face plate. That's the luck of fishing.